a(n) = ceiling(7^n/n).

Terms

a(0) =7a(1) =25a(2) =115a(3) =601a(4) =3362a(5) =19609a(6) =117649a(7) =720601a(8) =4483735a(9) =28247525a(10) =179756977a(11) =1153440601a(12) =7453000801a(13) =48444505204a(14) =316504100663